1. Field of the Invention
This invention relates to a display control device where in order to reduce power consumption, input data is stored to be sequentially displayed on a display screen and, particularly, to a display control device adapted to turn off a display unit as long as no change in a displayed content takes place.
2. Prior Art
A display control device is well known in which input data is stored in a memory and displayed sequentially on a screen. In such a display control device, a display controller-kernel unit delivers a control signal to a display panel, such as a liquid crystal display (LCD) panel or the like, in accordance with control instructions from an external unit, such as a central processing unit (CPU), to commence the control of the display panel and also stores data (character codes) fed from the CPU in a memory. The stored data are successively read from the memory, converted by the display controller-kernel unit to data to be displayed (character patterns) and fed to the display panel for display.
Since the above-referred display control device reads the content of the memory to cause it to be displayed on the display screen even when no change in displayed content takes place, there is a drawback in that power is consumed even when no data are required to be displayed.
It is well known to turn off a display screen when no data are required to be displayed. For example, Japanese Patent Public Disclosure No. 9634/86 laid open on Jan. 17, 1986 discloses a display control device for causing data to be displayed for a predetermined period of time in response to an operation of an input means. It is, however, necessary in such a prior art device to provide additional software to the control device and change the display controller-kernel unit, which will result in an increase in the size and cost of the device.
Japanese Patent Public Disclosure No. 112371/84 laid open on Jun. 28, 1984 also discloses a technique for automatically turning off a screen when a predetermined period of time for which the same image is displayed has lapsed. This technique also has such problems as mentioned above.